Before:
  enew!

Execute (:SSave foo | SClose):
  edit include/testfile.txt
  SSave foo
  SClose
Do (q):
  q
Expect (<blank>):
  

Execute (:SLoad foo):
  SLoad foo
Expect (textfile.txt):
  This is just a simple test file.
  Foo, bar, quux.

Execute (Session: :SDelete! foo):
  AssertEqual filereadable(g:startify_session_dir.'/foo'), 1
  SDelete! foo
  AssertEqual filereadable(g:startify_session_dir.'/foo'), 0